1. Field of the Invention
The present invention relates to a computer system with a monochrome display unit capable of converting a color code to a gradation code.
2. Description of the Related Art
Recently, a flat panel display such as an LCD (Liquid Crystal Display) or a PDP (Plasma Display Panel) has been used as a display unit of a portable computer system. However, many of application software used in the portable computer system are made for a color CRT. Therefore, if an image is directly displayed on a flat panel display capable of displaying only a monochrome image, colors cannot be discriminated from each other.
For this reason, a pseudo gradation method in which one dot is displayed using a plurality of dots or a method of displaying on a flat panel display with gradation are conventionally used. However, in the former method, a flat panel display must have a number of dots several times that of dots to be displayed. In the latter method, if gradation display is performed by 16 gray levels, adjacent gray levels cannot be discriminated, and the lightest display cannot be seen. To the contrary, if the number of gray levels is limited, a plurality of colors must be assigned to one gray level. As a result, colors cannot be discriminated from each other.